3/5 live K high flush vs. nit, facing heat

[tuckercat]

3/5, effective stacks are ~1500... i've been at the table for about 3 hours, and have run up my stack in fairly short order. the table is a standard local card room fish fest. tons of limping, calling, over calling, just overall terrible play. the main villain in question however has been nitty and fairly solid throughout my time there. i have no other history with him, and no real reads, other than the hands he's shown down have been strong, and he's been pretty tight/nitty for the most part. the second villain is an older vietnamese gentleman who is stuck at least 3 buyins from what i know, possibly more. total gambler, station, overall terrible player.

i'm in bb with KsTs... 6 limpers, i check option, flop comes Kd7s3s, i check, vietnamese guy (UTG) bets $30, nit (MP)calls , i call. turn is a 6s... i lead out $80, viet guy calls, nit raises to $180... i call, viet guy folds...thoughts on hand as played, what's the plan for river?